ListBox自画(100分)

我在ListBox里的item画一个图标时，第一行是画有图标但是其他行都没有画出图标
请帮忙找出原因，是我的代码有问题吗，在哪?
代码：
...
void __fastcall Tforml::ListBox1DrawItem(TWinControl *Control,
int Index, TRect &Rect, TOwnerDrawState State)
{
ListBox1->Canvas->FillRect(Rect);
ImageList1->Draw(ListBox1->Canvas, Rect.Left+margin, Rect.Top+margin, 0 , true);
int ioff = (Rect.Bottom - Rect.Top - ImageList1->Height)/2;
ImageList1->Draw(ListBox1->Canvas, Rect.Left+margin, ioff, 0 , true);
AnsiString text = lbAttachment->Items->Strings[Index];
int off = (Rect.Bottom - Rect.Top-ListBox1->Canvas->TextHeight(text))/2;
ListBox1->Canvas->TextOut(Rect.Left+ilListBox->Width+2*margin, Rect.Top+off,ListBox1->Items->Strings[Index]);
}